libstdc++
std::basic_filebuf< _CharT, _Traits > Class Template Reference
Inheritance diagram for std::basic_filebuf< _CharT, _Traits >:
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Public Types

typedef codecvt< char_type, char, __state_type > __codecvt_type
 
typedef __basic_file< char > __file_type
 
typedef basic_filebuf< char_type, traits_type > __filebuf_type
 
typedef traits_type::state_type __state_type
 
typedef basic_streambuf< char_type, traits_type > __streambuf_type
 
typedef _CharT char_type
 
typedef traits_type::int_type int_type
 
typedef traits_type::off_type off_type
 
typedef traits_type::pos_type pos_type
 
typedef _Traits traits_type
 

Public Member Functions

 basic_filebuf ()
 
 basic_filebuf (basic_filebuf &&)
 
 basic_filebuf (const basic_filebuf &)=delete
 
virtual ~basic_filebuf ()
 
__filebuf_typeclose ()
 
locale getloc () const
 
streamsize in_avail ()
 
bool is_open () const throw ()
 
template<typename _Path >
_If_fs_path< _Path, __filebuf_type * > open (const _Path &__s, ios_base::openmode __mode)
 
__filebuf_typeopen (const char *__s, ios_base::openmode __mode)
 
__filebuf_typeopen (const std::string &__s, ios_base::openmode __mode)
 
basic_filebufoperator= (basic_filebuf &&)
 
basic_filebufoperator= (const basic_filebuf &)=delete
 
locale pubimbue (const locale &__loc)
 
int_type sbumpc ()
 
int_type sgetc ()
 
streamsize sgetn (char_type *__s, streamsize __n)
 
int_type snextc ()
 
int_type sputbackc (char_type __c)
 
int_type sputc (char_type __c)
 
streamsize sputn (const char_type *__s, streamsize __n)
 
int_type sungetc ()
 
void swap (basic_filebuf &)
 
basic_streambufpubsetbuf (char_type *__s, streamsize __n)
 
pos_type pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
 
pos_type pubseekpos (pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out)
 
int pubsync ()
 

Protected Member Functions

void __safe_gbump (streamsize __n)
 
void __safe_pbump (streamsize __n)
 
void _M_allocate_internal_buffer ()
 
bool _M_convert_to_external (char_type *, streamsize)
 
void _M_create_pback ()
 
void _M_destroy_internal_buffer () throw ()
 
void _M_destroy_pback () throw ()
 
int _M_get_ext_pos (__state_type &__state)
 
pos_type _M_seek (off_type __off, ios_base::seekdir __way, __state_type __state)
 
void _M_set_buffer (streamsize __off)
 
bool _M_terminate_output ()
 
void gbump (int __n)
 
virtual void imbue (const locale &__loc)
 
virtual int_type overflow (int_type __c=_Traits::eof())
 
virtual int_type pbackfail (int_type __c=_Traits::eof())
 
void pbump (int __n)
 
virtual pos_type seekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
 
virtual pos_type seekpos (pos_type __pos, ios_base::openmode __mode=ios_base::in|ios_base::out)
 
virtual __streambuf_typesetbuf (char_type *__s, streamsize __n)
 
void setg (char_type *__gbeg, char_type *__gnext, char_type *__gend)
 
void setp (char_type *__pbeg, char_type *__pend)
 
virtual streamsize showmanyc ()
 
void swap (basic_streambuf &__sb)
 
virtual int sync ()
 
virtual int_type uflow ()
 
virtual int_type underflow ()
 
virtual streamsize xsgetn (char_type *__s, streamsize __n)
 
virtual streamsize xsputn (const char_type *__s, streamsize __n)
 
char_type * eback () const
 
char_type * gptr () const
 
char_type * egptr () const
 
char_type * pbase () const
 
char_type * pptr () const
 
char_type * epptr () const
 

Protected Attributes

char_type * _M_buf
 
bool _M_buf_allocated
 
locale _M_buf_locale
 
size_t _M_buf_size
 
const __codecvt_type_M_codecvt
 
char * _M_ext_buf
 
streamsize _M_ext_buf_size
 
char * _M_ext_end
 
const char * _M_ext_next
 
__file_type _M_file
 
char_type * _M_in_beg
 
char_type * _M_in_cur
 
char_type * _M_in_end
 
__c_lock _M_lock
 
ios_base::openmode _M_mode
 
char_type * _M_out_beg
 
char_type * _M_out_cur
 
char_type * _M_out_end
 
bool _M_reading
 
__state_type _M_state_beg
 
__state_type _M_state_cur
 
__state_type _M_state_last
 
bool _M_writing
 
char_type _M_pback
 
char_type * _M_pback_cur_save
 
char_type * _M_pback_end_save
 
bool _M_pback_init
 

Friends

class ios_base
 

Detailed Description

template<typename _CharT, typename _Traits>
class std::basic_filebuf< _CharT, _Traits >

The actual work of input and output (for files).

Template Parameters
_CharTType of character stream.
_TraitsTraits for character type, defaults to char_traits<_CharT>.

This class associates both its input and output sequence with an external disk file, and maintains a joint file position for both sequences. Many of its semantics are described in terms of similar behavior in the Standard C Library's FILE streams.

Requirements on traits_type, specific to this class:

  • traits_type::pos_type must be fpos<traits_type::state_type>
  • traits_type::off_type must be streamoff
  • traits_type::state_type must be Assignable and DefaultConstructible,
  • traits_type::state_type() must be the initial state for codecvt.

Definition at line 85 of file fstream.

Constructor & Destructor Documentation

◆ basic_filebuf()

template<typename _CharT , typename _Traits >
std::basic_filebuf< _CharT, _Traits >::basic_filebuf

Does not open any files.

The default constructor initializes the parent class using its own default ctor.

Definition at line 80 of file fstream.tcc.

◆ ~basic_filebuf()

template<typename _CharT , typename _Traits >
virtual std::basic_filebuf< _CharT, _Traits >::~basic_filebuf ( )
inlinevirtual

The destructor closes the file first.

Definition at line 251 of file fstream.

Member Function Documentation

◆ _M_create_pback()

template<typename _CharT , typename _Traits >
void std::basic_filebuf< _CharT, _Traits >::_M_create_pback ( )
inlineprotected

◆ _M_destroy_pback()

template<typename _CharT , typename _Traits >
void std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback ( )
throw (
)
inlineprotected

◆ _M_set_buffer()

template<typename _CharT , typename _Traits >
void std::basic_filebuf< _CharT, _Traits >::_M_set_buffer ( streamsize  __off)
inlineprotected

This function sets the pointers of the internal buffer, both get and put areas. Typically:

__off == egptr() - eback() upon underflow/uflow (read mode); __off == 0 upon overflow (write mode); __off == -1 upon open, setbuf, seekoff/pos (uncommitted mode).

NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size reflects the actual allocated memory and the last cell is reserved for the overflow char of a full put area.

Definition at line 464 of file fstream.

References std::basic_filebuf< _CharT, _Traits >::_M_buf, std::basic_filebuf< _CharT, _Traits >::_M_buf_size, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::ios_base::app, std::ios_base::in, std::ios_base::out, std::basic_streambuf< _CharT, _Traits >::setg(), and std::basic_streambuf< _CharT, _Traits >::setp().

Referenced by std::basic_filebuf< _CharT, _Traits >::close().

◆ close()

template<typename _CharT , typename _Traits >
basic_filebuf< _CharT, _Traits >::__filebuf_type * std::basic_filebuf< _CharT, _Traits >::close

Closes the currently associated file.

Returns
this on success, NULL on failure

If no file is currently open, this function immediately fails.

If a put buffer area exists, overflow(eof) is called to flush all the characters. The file is then closed.

If any operations fail, this function also fails.

Definition at line 249 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_pback_init, std::basic_filebuf< _CharT, _Traits >::_M_reading, and std::basic_filebuf< _CharT, _Traits >::_M_set_buffer().

Referenced by std::basic_ifstream< _CharT, _Traits >::close(), std::basic_ofstream< _CharT, _Traits >::close(), and std::basic_fstream< _CharT, _Traits >::close().

◆ eback()

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::eback ( ) const
inlineprotectedinherited

Access to the get area.

These functions are only available to other protected functions, including derived classes.

  • eback() returns the beginning pointer for the input sequence
  • gptr() returns the next pointer for the input sequence
  • egptr() returns the end pointer for the input sequence

Definition at line 487 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_in_beg.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback(), std::basic_streambuf< _CharT, _Traits >::sputbackc(), and std::basic_streambuf< _CharT, _Traits >::sungetc().

◆ egptr()

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::egptr ( ) const
inlineprotectedinherited

Access to the get area.

These functions are only available to other protected functions, including derived classes.

  • eback() returns the beginning pointer for the input sequence
  • gptr() returns the next pointer for the input sequence
  • egptr() returns the end pointer for the input sequence

Definition at line 493 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_in_end.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_create_pback(), std::basic_streambuf< _CharT, _Traits >::in_avail(), std::basic_streambuf< _CharT, _Traits >::sbumpc(), std::basic_streambuf< _CharT, _Traits >::sgetc(), and std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc().

◆ epptr()

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::epptr ( ) const
inlineprotectedinherited

Access to the put area.

These functions are only available to other protected functions, including derived classes.

  • pbase() returns the beginning pointer for the output sequence
  • pptr() returns the next pointer for the output sequence
  • epptr() returns the end pointer for the output sequence

Definition at line 540 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_out_end.

Referenced by std::basic_streambuf< _CharT, _Traits >::sputc().

◆ gbump()

template<typename _CharT , typename _Traits >
void std::basic_streambuf< _CharT, _Traits >::gbump ( int  __n)
inlineprotectedinherited

Moving the read position.

Parameters
__nThe delta by which to move.

This just advances the read position without returning any data.

Definition at line 503 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_in_cur.

Referenced by std::basic_streambuf< _CharT, _Traits >::sbumpc(), std::basic_streambuf< _CharT, _Traits >::sputbackc(), std::basic_streambuf< _CharT, _Traits >::sungetc(), and std::basic_streambuf< _CharT, _Traits >::uflow().

◆ getloc()

template<typename _CharT , typename _Traits >
locale std::basic_streambuf< _CharT, _Traits >::getloc ( ) const
inlineinherited

Locale access.

Returns
The current locale in effect.

If pubimbue(loc) has been called, then the most recent loc is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 231 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_buf_locale.

Referenced by std::basic_streambuf< _CharT, _Traits >::pubimbue().

◆ gptr()

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::gptr ( ) const
inlineprotectedinherited

Access to the get area.

These functions are only available to other protected functions, including derived classes.

  • eback() returns the beginning pointer for the input sequence
  • gptr() returns the next pointer for the input sequence
  • egptr() returns the end pointer for the input sequence

Definition at line 490 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_in_cur.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_create_pback(), std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback(), std::basic_streambuf< _CharT, _Traits >::in_avail(), std::basic_streambuf< _CharT, _Traits >::sbumpc(), std::basic_streambuf< _CharT, _Traits >::sgetc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::showmanyc(), std::basic_streambuf< _CharT, _Traits >::sputbackc(), std::basic_streambuf< _CharT, _Traits >::sungetc(), and std::basic_streambuf< _CharT, _Traits >::uflow().

◆ imbue()

template<typename _CharT , typename _Traits >
void std::basic_filebuf< _CharT, _Traits >::imbue ( const locale __loc)
protectedvirtual

Changes translations.

Parameters
__locA new locale.

Translations done during I/O which depend on the current locale are changed by this call. The standard adds, Between invocations of this function a class derived from streambuf can safely cache results of calls to locale functions and to members of facets so obtained.

Note
Base class version does nothing.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 1029 of file fstream.tcc.

References std::ios_base::cur.

◆ in_avail()

template<typename _CharT , typename _Traits >
streamsize std::basic_streambuf< _CharT, _Traits >::in_avail ( )
inlineinherited

Looking ahead into the stream.

Returns
The number of characters available.

If a read position is available, returns the number of characters available for reading before the buffer must be refilled. Otherwise returns the derived showmanyc().

Definition at line 289 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::showmanyc().

◆ is_open()

template<typename _CharT , typename _Traits >
bool std::basic_filebuf< _CharT, _Traits >::is_open ( ) const
throw (
)
inline

◆ open() [1/3]

template<typename _CharT , typename _Traits >
template<typename _Path >
_If_fs_path<_Path, __filebuf_type*> std::basic_filebuf< _CharT, _Traits >::open ( const _Path &  __s,
ios_base::openmode  __mode 
)
inline

Opens an external file.

Parameters
__sThe name of the file, as a filesystem::path.
__modeThe open mode flags.
Returns
this on success, NULL on failure

Definition at line 348 of file fstream.

References std::basic_filebuf< _CharT, _Traits >::open().

◆ open() [2/3]

template<typename _CharT , typename _Traits >
basic_filebuf< _CharT, _Traits >::__filebuf_type * std::basic_filebuf< _CharT, _Traits >::open ( const char *  __s,
ios_base::openmode  __mode 
)

Opens an external file.

Parameters
__sThe name of the file.
__modeThe open mode flags.
Returns
this on success, NULL on failure

If a file is already open, this function immediately fails. Otherwise it tries to open the file named __s using the flags given in __mode.

Table 92, adapted here, gives the relation between openmode combinations and the equivalent fopen() flags. (NB: lines app, in|out|app, in|app, binary|app, binary|in|out|app, and binary|in|app per DR 596)

+---------------------------------------------------------+
| ios_base Flag combination            stdio equivalent   |
|binary  in  out  trunc  app                              |
+---------------------------------------------------------+
|             +                        w                  |
|             +           +            a                  |
|                         +            a                  |
|             +     +                  w                  |
|         +                            r                  |
|         +   +                        r+                 |
|         +   +     +                  w+                 |
|         +   +           +            a+                 |
|         +               +            a+                 |
+---------------------------------------------------------+
|   +         +                        wb                 |
|   +         +           +            ab                 |
|   +                     +            ab                 |
|   +         +     +                  wb                 |
|   +     +                            rb                 |
|   +     +   +                        r+b                |
|   +     +   +     +                  w+b                |
|   +     +   +           +            a+b                |
|   +     +               +            a+b                |
+---------------------------------------------------------+

Definition at line 179 of file fstream.tcc.

References std::ios_base::ate, std::ios_base::end, and std::basic_filebuf< _CharT, _Traits >::open().

Referenced by std::basic_ifstream< _CharT, _Traits >::open(), std::basic_fstream< _CharT, _Traits >::open(), std::basic_ofstream< _CharT, _Traits >::open(), and std::basic_filebuf< _CharT, _Traits >::open().

◆ open() [3/3]

template<typename _CharT , typename _Traits >
__filebuf_type* std::basic_filebuf< _CharT, _Traits >::open ( const std::string __s,
ios_base::openmode  __mode 
)
inline

Opens an external file.

Parameters
__sThe name of the file.
__modeThe open mode flags.
Returns
this on success, NULL on failure

Definition at line 336 of file fstream.

References std::basic_string< _CharT, _Traits, _Alloc >::c_str(), and std::basic_filebuf< _CharT, _Traits >::open().

◆ overflow()

template<typename _CharT , typename _Traits >
basic_filebuf< _CharT, _Traits >::int_type std::basic_filebuf< _CharT, _Traits >::overflow ( int_type  __c = _Traits::eof())
protectedvirtual

Consumes data from the buffer; writes to the controlled sequence.

Parameters
__cAn additional character to consume.
Returns
eof() to indicate failure, something else (usually __c, or not_eof())

Informally, this function is called when the output buffer is full (or does not exist, as buffering need not actually be done). If a buffer exists, it is consumed, with some effect on the controlled sequence. (Typically, the buffer is written out to the sequence verbatim.) In either case, the character c is also written out, if __c is not eof().

For a formal definition of this function, see a good text such as Langer & Kreft, or [27.5.2.4.5]/3-7.

A functioning output streambuf can be created by overriding only this function (no buffer area will be used).

Note
Base class version does nothing, returns eof().

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 541 of file fstream.tcc.

References std::ios_base::app, std::ios_base::cur, and std::ios_base::out.

◆ pbackfail()

template<typename _CharT , typename _Traits >
basic_filebuf< _CharT, _Traits >::int_type std::basic_filebuf< _CharT, _Traits >::pbackfail ( int_type  __c = _Traits::eof())
protectedvirtual

Tries to back up the input sequence.

Parameters
__cThe character to be inserted back into the sequence.
Returns
eof() on failure, some other value on success
Postcondition
The constraints of gptr(), eback(), and pptr() are the same as for underflow().
Note
Base class version does nothing, returns eof().

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 482 of file fstream.tcc.

References std::ios_base::cur, and std::ios_base::in.

◆ pbase()

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::pbase ( ) const
inlineprotectedinherited

Access to the put area.

These functions are only available to other protected functions, including derived classes.

  • pbase() returns the beginning pointer for the output sequence
  • pptr() returns the next pointer for the output sequence
  • epptr() returns the end pointer for the output sequence

Definition at line 534 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_out_beg.

◆ pbump()

template<typename _CharT , typename _Traits >
void std::basic_streambuf< _CharT, _Traits >::pbump ( int  __n)
inlineprotectedinherited

Moving the write position.

Parameters
__nThe delta by which to move.

This just advances the write position without returning any data.

Definition at line 550 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_out_cur.

Referenced by std::basic_streambuf< _CharT, _Traits >::sputc().

◆ pptr()

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::pptr ( ) const
inlineprotectedinherited

Access to the put area.

These functions are only available to other protected functions, including derived classes.

  • pbase() returns the beginning pointer for the output sequence
  • pptr() returns the next pointer for the output sequence
  • epptr() returns the end pointer for the output sequence

Definition at line 537 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_out_cur.

Referenced by std::basic_streambuf< _CharT, _Traits >::sputc().

◆ pubimbue()

template<typename _CharT , typename _Traits >
locale std::basic_streambuf< _CharT, _Traits >::pubimbue ( const locale __loc)
inlineinherited

Entry point for imbue().

Parameters
__locThe new locale.
Returns
The previous locale.

Calls the derived imbue(__loc).

Definition at line 214 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_buf_locale, std::basic_streambuf< _CharT, _Traits >::getloc(), and std::basic_streambuf< _CharT, _Traits >::imbue().

◆ pubseekoff()

template<typename _CharT , typename _Traits >
pos_type std::basic_streambuf< _CharT, _Traits >::pubseekoff ( off_type  __off,
ios_base::seekdir  __way,
ios_base::openmode  __mode = ios_base::in | ios_base::out 
)
inlineinherited

Alters the stream position.

Parameters
__offOffset.
__wayValue for ios_base::seekdir.
__modeValue for ios_base::openmode.

Calls virtual seekoff function.

Definition at line 256 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::seekoff().

◆ pubseekpos()

template<typename _CharT , typename _Traits >
pos_type std::basic_streambuf< _CharT, _Traits >::pubseekpos ( pos_type  __sp,
ios_base::openmode  __mode = ios_base::in | ios_base::out 
)
inlineinherited

Alters the stream position.

Parameters
__spPosition
__modeValue for ios_base::openmode.

Calls virtual seekpos function.

Definition at line 268 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::seekpos().

◆ pubsetbuf()

template<typename _CharT , typename _Traits >
basic_streambuf* std::basic_streambuf< _CharT, _Traits >::pubsetbuf ( char_type __s,
streamsize  __n 
)
inlineinherited

Entry points for derived buffer functions.

The public versions of pubfoo dispatch to the protected derived foo member functions, passing the arguments (if any) and returning the result unchanged.

Definition at line 244 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::setbuf().

◆ pubsync()

template<typename _CharT , typename _Traits >
int std::basic_streambuf< _CharT, _Traits >::pubsync ( )
inlineinherited

Calls virtual sync function.

Definition at line 276 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::sync().

Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::sync().

◆ sbumpc()

template<typename _CharT , typename _Traits >
int_type std::basic_streambuf< _CharT, _Traits >::sbumpc ( )
inlineinherited

Getting the next character.

Returns
The next character, or eof.

If the input read position is available, returns that character and increments the read pointer, otherwise calls and returns uflow().

Definition at line 321 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::uflow().

Referenced by std::basic_streambuf< _CharT, _Traits >::snextc().

◆ seekoff()

template<typename _CharT , typename _Traits >
basic_filebuf< _CharT, _Traits >::pos_type std::basic_filebuf< _CharT, _Traits >::seekoff ( off_type  ,
ios_base::seekdir  ,
ios_base::openmode  = ios_base::in | ios_base::out 
)
protectedvirtual

Alters the stream positions.

Each derived class provides its own appropriate behavior.

Note
Base class version does nothing, returns a pos_type that represents an invalid stream position.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 832 of file fstream.tcc.

References std::ios_base::cur.

◆ seekpos()

template<typename _CharT , typename _Traits >
basic_filebuf< _CharT, _Traits >::pos_type std::basic_filebuf< _CharT, _Traits >::seekpos ( pos_type  ,
ios_base::openmode  = ios_base::in | ios_base::out 
)
protectedvirtual

Alters the stream positions.

Each derived class provides its own appropriate behavior.

Note
Base class version does nothing, returns a pos_type that represents an invalid stream position.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 892 of file fstream.tcc.

References std::ios_base::beg.

◆ setbuf()

template<typename _CharT , typename _Traits >
basic_filebuf< _CharT, _Traits >::__streambuf_type * std::basic_filebuf< _CharT, _Traits >::setbuf ( char_type *  __s,
streamsize  __n 
)
protectedvirtual

Manipulates the buffer.

Parameters
__sPointer to a buffer area.
__nSize of __s.
Returns
this

If no file has been opened, and both __s and __n are zero, then the stream becomes unbuffered. Otherwise, __s is used as a buffer; see https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering for more.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 803 of file fstream.tcc.

◆ setg()

template<typename _CharT , typename _Traits >
void std::basic_streambuf< _CharT, _Traits >::setg ( char_type __gbeg,
char_type __gnext,
char_type __gend 
)
inlineprotectedinherited

Setting the three read area pointers.

Parameters
__gbegA pointer.
__gnextA pointer.
__gendA pointer.
Postcondition
__gbeg == eback(), __gnext == gptr(), and __gend == egptr()

Definition at line 514 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_in_beg, std::basic_streambuf< _CharT, _Traits >::_M_in_cur, and std::basic_streambuf< _CharT, _Traits >::_M_in_end.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_create_pback(), std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback(), and std::basic_filebuf< _CharT, _Traits >::_M_set_buffer().

◆ setp()

template<typename _CharT , typename _Traits >
void std::basic_streambuf< _CharT, _Traits >::setp ( char_type __pbeg,
char_type __pend 
)
inlineprotectedinherited

Setting the three write area pointers.

Parameters
__pbegA pointer.
__pendA pointer.
Postcondition
__pbeg == pbase(), __pbeg == pptr(), and __pend == epptr()

Definition at line 560 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::_M_out_beg, std::basic_streambuf< _CharT, _Traits >::_M_out_cur, and std::basic_streambuf< _CharT, _Traits >::_M_out_end.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_set_buffer().

◆ sgetc()

template<typename _CharT , typename _Traits >
int_type std::basic_streambuf< _CharT, _Traits >::sgetc ( )
inlineinherited

Getting the next character.

Returns
The next character, or eof.

If the input read position is available, returns that character, otherwise calls and returns underflow(). Does not move the read position after fetching the character.

Definition at line 343 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::underflow().

Referenced by std::basic_istream< char >::seekg(), and std::basic_streambuf< _CharT, _Traits >::snextc().

◆ sgetn()

template<typename _CharT , typename _Traits >
streamsize std::basic_streambuf< _CharT, _Traits >::sgetn ( char_type __s,
streamsize  __n 
)
inlineinherited

Entry point for xsgetn.

Parameters
__sA buffer area.
__nA count.

Returns xsgetn(__s,__n). The effect is to fill __s[0] through __s[__n-1] with characters from the input sequence, if possible.

Definition at line 362 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::xsgetn().

◆ showmanyc()

template<typename _CharT , typename _Traits >
streamsize std::basic_filebuf< _CharT, _Traits >::showmanyc
protectedvirtual

Investigating the data available.

Returns
An estimate of the number of characters available in the input sequence, or -1.

If it returns a positive value, then successive calls to underflow() will not return traits::eof() until at least that number of characters have been supplied. If showmanyc() returns -1, then calls to underflow() or uflow() will fail. [27.5.2.4.3]/1

Note
Base class version does nothing, returns zero.
The standard adds that the intention is not only that the calls [to underflow or uflow] will not return eof() but that they will return immediately.
The standard adds that the morphemes of showmanyc are es-how-many-see, not show-manic.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 297 of file fstream.tcc.

References std::ios_base::binary, and std::ios_base::in.

◆ snextc()

template<typename _CharT , typename _Traits >
int_type std::basic_streambuf< _CharT, _Traits >::snextc ( )
inlineinherited

Getting the next character.

Returns
The next character, or eof.

Calls sbumpc(), and if that function returns traits::eof(), so does this function. Otherwise, sgetc().

Definition at line 303 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::sbumpc(), and std::basic_streambuf< _CharT, _Traits >::sgetc().

Referenced by std::basic_istream< char >::putback(), and std::basic_istream< char >::seekg().

◆ sputbackc()

template<typename _CharT , typename _Traits >
int_type std::basic_streambuf< _CharT, _Traits >::sputbackc ( char_type  __c)
inlineinherited

Pushing characters back into the input stream.

Parameters
__cThe character to push back.
Returns
The previous character, if possible.

Similar to sungetc(), but __c is pushed onto the stream instead of the previous character. If successful, the next character fetched from the input stream will be __c.

Definition at line 377 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::eback(), std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::pbackfail().

◆ sputc()

template<typename _CharT , typename _Traits >
int_type std::basic_streambuf< _CharT, _Traits >::sputc ( char_type  __c)
inlineinherited

Entry point for all single-character output functions.

Parameters
__cA character to output.
Returns
__c, if possible.

One of two public output functions.

If a write position is available for the output sequence (i.e., the buffer is not full), stores __c in that position, increments the position, and returns traits::to_int_type(__c). If a write position is not available, returns overflow(__c).

Definition at line 429 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::epptr(), std::basic_streambuf< _CharT, _Traits >::overflow(), std::basic_streambuf< _CharT, _Traits >::pbump(), and std::basic_streambuf< _CharT, _Traits >::pptr().

Referenced by std::ostreambuf_iterator< _CharT, _Traits >::operator=().

◆ sputn()

template<typename _CharT , typename _Traits >
streamsize std::basic_streambuf< _CharT, _Traits >::sputn ( const char_type __s,
streamsize  __n 
)
inlineinherited

Entry point for all single-character output functions.

Parameters
__sA buffer read area.
__nA count.

One of two public output functions.

Returns xsputn(__s,__n). The effect is to write __s[0] through __s[__n-1] to the output sequence, if possible.

Definition at line 455 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::xsputn().

◆ sungetc()

template<typename _CharT , typename _Traits >
int_type std::basic_streambuf< _CharT, _Traits >::sungetc ( )
inlineinherited

Moving backwards in the input stream.

Returns
The previous character, if possible.

If a putback position is available, this function decrements the input pointer and returns that character. Otherwise, calls and returns pbackfail(). The effect is to unget the last character gotten.

Definition at line 402 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::eback(), std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::pbackfail().

◆ sync()

template<typename _CharT , typename _Traits >
int std::basic_filebuf< _CharT, _Traits >::sync
protectedvirtual

Synchronizes the buffer arrays with the controlled sequences.

Returns
-1 on failure.

Each derived class provides its own appropriate behavior, including the definition of failure.

Note
Base class version does nothing, returns zero.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 1012 of file fstream.tcc.

◆ uflow()

template<typename _CharT , typename _Traits >
virtual int_type std::basic_streambuf< _CharT, _Traits >::uflow ( )
inlineprotectedvirtualinherited

Fetches more data from the controlled sequence.

Returns
The first character from the pending sequence.

Informally, this function does the same thing as underflow(), and in fact is required to call that function. It also returns the new character, like underflow() does. However, this function also moves the read position forward by one.

Reimplemented in __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.

Definition at line 705 of file streambuf.

References std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), and std::basic_streambuf< _CharT, _Traits >::underflow().

Referenced by std::basic_streambuf< _CharT, _Traits >::sbumpc().

◆ underflow()

template<typename _CharT , typename _Traits >
basic_filebuf< _CharT, _Traits >::int_type std::basic_filebuf< _CharT, _Traits >::underflow
protectedvirtual

Fetches more data from the controlled sequence.

Returns
The first character from the pending sequence.

Informally, this function is called when the input buffer is exhausted (or does not exist, as buffering need not actually be done). If a buffer exists, it is refilled. In either case, the next available character is returned, or traits::eof() to indicate a null pending sequence.

For a formal definition of the pending sequence, see a good text such as Langer & Kreft, or [27.5.2.4.3]/7-14.

A functioning input streambuf can be created by overriding only this function (no buffer area will be used). For an example, see https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html

Note
Base class version does nothing, returns eof().

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 323 of file fstream.tcc.

References std::ios_base::in.

◆ xsgetn()

template<typename _CharT , typename _Traits >
streamsize std::basic_filebuf< _CharT, _Traits >::xsgetn ( char_type *  __s,
streamsize  __n 
)
protectedvirtual

Multiple character extraction.

Parameters
__sA buffer area.
__nMaximum number of characters to assign.
Returns
The number of characters assigned.

Fills __s[0] through __s[__n-1] with characters from the input sequence, as if by sbumpc(). Stops when either __n characters have been copied, or when traits::eof() would be copied.

It is expected that derived classes provide a more efficient implementation by overriding this definition.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 669 of file fstream.tcc.

References std::ios_base::in.

◆ xsputn()

template<typename _CharT , typename _Traits >
streamsize std::basic_filebuf< _CharT, _Traits >::xsputn ( const char_type *  __s,
streamsize  __n 
)
protectedvirtual

Multiple character insertion.

Parameters
__sA buffer area.
__nMaximum number of characters to write.
Returns
The number of characters written.

Writes __s[0] through __s[__n-1] to the output sequence, as if by sputc(). Stops when either n characters have been copied, or when sputc() would return traits::eof().

It is expected that derived classes provide a more efficient implementation by overriding this definition.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 755 of file fstream.tcc.

References std::ios_base::app, std::min(), and std::ios_base::out.

Member Data Documentation

◆ _M_buf

template<typename _CharT , typename _Traits >
char_type* std::basic_filebuf< _CharT, _Traits >::_M_buf
protected

Pointer to the beginning of internal buffer.

Definition at line 141 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_set_buffer().

◆ _M_buf_locale

template<typename _CharT , typename _Traits >
locale std::basic_streambuf< _CharT, _Traits >::_M_buf_locale
protectedinherited

Current locale setting.

Definition at line 197 of file streambuf.

Referenced by std::basic_streambuf< _CharT, _Traits >::getloc(), and std::basic_streambuf< _CharT, _Traits >::pubimbue().

◆ _M_buf_size

template<typename _CharT , typename _Traits >
size_t std::basic_filebuf< _CharT, _Traits >::_M_buf_size
protected

Actual size of internal buffer. This number is equal to the size of the put area + 1 position, reserved for the overflow char of a full area.

Definition at line 148 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_set_buffer().

◆ _M_ext_buf

template<typename _CharT , typename _Traits >
char* std::basic_filebuf< _CharT, _Traits >::_M_ext_buf
protected

Buffer for external characters. Used for input when codecvt::always_noconv() == false. When valid, this corresponds to eback().

Definition at line 183 of file fstream.

◆ _M_ext_buf_size

template<typename _CharT , typename _Traits >
streamsize std::basic_filebuf< _CharT, _Traits >::_M_ext_buf_size
protected

Size of buffer held by _M_ext_buf.

Definition at line 188 of file fstream.

◆ _M_ext_next

template<typename _CharT , typename _Traits >
const char* std::basic_filebuf< _CharT, _Traits >::_M_ext_next
protected

Pointers into the buffer held by _M_ext_buf that delimit a subsequence of bytes that have been read but not yet converted. When valid, _M_ext_next corresponds to egptr().

Definition at line 195 of file fstream.

◆ _M_in_beg

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_beg
protectedinherited

Start of get area.

Definition at line 189 of file streambuf.

Referenced by std::basic_streambuf< _CharT, _Traits >::eback(), and std::basic_streambuf< _CharT, _Traits >::setg().

◆ _M_in_cur

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_cur
protectedinherited

◆ _M_in_end

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_end
protectedinherited

◆ _M_mode

template<typename _CharT , typename _Traits >
ios_base::openmode std::basic_filebuf< _CharT, _Traits >::_M_mode
protected

Place to stash in || out || in | out settings for current filebuf.

Definition at line 126 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), and std::basic_filebuf< _CharT, _Traits >::close().

◆ _M_out_beg

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_beg
protectedinherited

Start of put area.

Definition at line 192 of file streambuf.

Referenced by std::basic_streambuf< _CharT, _Traits >::pbase(), and std::basic_streambuf< _CharT, _Traits >::setp().

◆ _M_out_cur

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_cur
protectedinherited

◆ _M_out_end

template<typename _CharT , typename _Traits >
char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_end
protectedinherited

◆ _M_pback

template<typename _CharT , typename _Traits >
char_type std::basic_filebuf< _CharT, _Traits >::_M_pback
protected

Necessary bits for putback buffer management.

Note
pbacks of over one character are not currently supported.

Definition at line 169 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_create_pback().

◆ _M_pback_cur_save

template<typename _CharT , typename _Traits >
char_type* std::basic_filebuf< _CharT, _Traits >::_M_pback_cur_save
protected

Necessary bits for putback buffer management.

Note
pbacks of over one character are not currently supported.

Definition at line 170 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_create_pback(), and std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback().

◆ _M_pback_end_save

template<typename _CharT , typename _Traits >
char_type* std::basic_filebuf< _CharT, _Traits >::_M_pback_end_save
protected

Necessary bits for putback buffer management.

Note
pbacks of over one character are not currently supported.

Definition at line 171 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback().

◆ _M_pback_init

template<typename _CharT , typename _Traits >
bool std::basic_filebuf< _CharT, _Traits >::_M_pback_init
protected

Necessary bits for putback buffer management.

Note
pbacks of over one character are not currently supported.

Definition at line 172 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_create_pback(), std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback(), and std::basic_filebuf< _CharT, _Traits >::close().

◆ _M_reading

template<typename _CharT , typename _Traits >
bool std::basic_filebuf< _CharT, _Traits >::_M_reading
protected

_M_reading == false && _M_writing == false for uncommitted mode; _M_reading == true for read mode; _M_writing == true for write mode;

NB: _M_reading == true && _M_writing == true is unused.

Definition at line 160 of file fstream.

Referenced by std::basic_filebuf< _CharT, _Traits >::close().


The documentation for this class was generated from the following files: